11. Redis implements follow, unfollow, and follow and follower lists

实现关注、取消关注

• value的数据类型时zset,有序集合,Sort by time of interest

followee:userId:entityType -> zset(entityId,now) 某个用户关注的实体(Entities include posts、评论、用户),Stored separately by entity
follower:entityType:entityId -> zset(userId,now) 某个实体拥有的粉丝（Entities include posts、评论、用户）

• This function is requested asynchronously

1、RedisKeyUtil

    private static final String PREFIX_FOLLOWEE = "followee";
    private static final String PREFIX_FOLLOWER = "follower";

    // 某个用户关注的实体(Entities include posts、用户)
    // followee:userId:entityType -> zset(entityId,now)
    public static String getFolloweeKey(int userId, int entityType) {
    
        return PREFIX_FOLLOWEE + SPLIT + userId + SPLIT + entityType;
    }

    // 某个实体拥有的粉丝（Entities include posts、用户）
    // follower:entityType:entityId -> zset(userId,now)
    public static String getFollowerKey(int entityType, int entityId) {
    
        return PREFIX_FOLLOWER + SPLIT + entityType + SPLIT + entityId;
    }

2、FollowService

@Service
public class FollowService {
    

    @Autowired
    private RedisTemplate redisTemplate;

    public void follow(int userId, int entityType, int entityId) {
    
        redisTemplate.execute(new SessionCallback() {
    
            @Override
            public Object execute(RedisOperations operations) throws DataAccessException {
    
            	// 某个用户关注的实体
                String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
                // 某个实体拥有的粉丝
                String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);

                operations.multi();

                operations.opsForZSet().add(followeeKey, entityId, System.currentTimeMillis());
                operations.opsForZSet().add(followerKey, userId, System.currentTimeMillis());

                return operations.exec();
            }
        });
    }

    public void unfollow(int userId, int entityType, int entityId) {
    
        redisTemplate.execute(new SessionCallback() {
    
            @Override
            public Object execute(RedisOperations operations) throws DataAccessException {
    
                String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
                String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);

                operations.multi();

                operations.opsForZSet().remove(followeeKey, entityId);
                operations.opsForZSet().remove(followerKey, userId);

                return operations.exec();
            }
        });
    }

    // 查询关注的实体的数量
    public long findFolloweeCount(int userId, int entityType) {
    
        String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
        return redisTemplate.opsForZSet().zCard(followeeKey);
    }

    // 查询实体的粉丝的数量
    public long findFollowerCount(int entityType, int entityId){
    
        String followerKey = RedisKeyUtil.getFollowerKey(entityType, entityId);
        return redisTemplate.opsForZSet().zCard(followerKey);
    }

    // 查询当前用户是否已关注该实体(the user to such entitiesid有一个清单zset)
    public boolean hasFollowed(int userId, int entityType, int entityId) {
    
        String followeeKey = RedisKeyUtil.getFolloweeKey(userId, entityType);
        return redisTemplate.opsForZSet().score(followeeKey, entityId) != null;
    }

}

3、profile.js

$(function(){
    
	$(".follow-btn").click(follow);
});

function follow() {
    
	var btn = this;
	if($(btn).hasClass("btn-info")) {
    
		// 关注TA
		$.post(
			CONTEXT_PATH + "/follow",
			{
    "entityType":3,"entityId":$(btn).prev().val()},
			function(data) {
    
				data = $.parseJSON(data);
				if(data.code == 0) {
    
					window.location.reload();
				} else {
    
					alert(data.msg);
				}
			}
		);
		// $(btn).text("已关注").removeClass("btn-info").addClass("btn-secondary");
	} else {
    
		// 取消关注
		$.post(
			CONTEXT_PATH + "/unfollow",
			{
    "entityType":3,"entityId":$(btn).prev().val()},
			function(data) {
    
				data = $.parseJSON(data);
				if(data.code == 0) {
    
					window.location.reload();
				} else {
    
					alert(data.msg);
				}
			}
		);
		//$(btn).text("关注TA").removeClass("btn-secondary").addClass("btn-info");
	}
}

关注列表和粉丝列表

1、FollowService

    // 查询某用户关注的人
    public List<Map<String, Object>> findFollowees(int userId, int offset, int limit) {
    
        String followeeKey = RedisKeyUtil.getFolloweeKey(userId, ENTITY_TYPE_USER);
        Set<Integer> targetIds = redisTemplate.opsForZSet().reverseRange(followeeKey, offset, offset + limit - 1);

        if (targetIds == null) {
    
            return null;
        }

        List<Map<String, Object>> list = new ArrayList<>();
        for (Integer targetId : targetIds) {
    
            Map<String, Object> map = new HashMap<>();
            User user = userService.findUserById(targetId);
            map.put("user", user);
            Double score = redisTemplate.opsForZSet().score(followeeKey, targetId);
            map.put("followTime", new Date(score.longValue()));
            list.add(map);
        }

        return list;
    }

    // 查询某用户的粉丝
    public List<Map<String, Object>> findFollowers(int userId, int offset, int limit) {
    
        String followerKey = RedisKeyUtil.getFollowerKey(ENTITY_TYPE_USER, userId);
        Set<Integer> targetIds = redisTemplate.opsForZSet().reverseRange(followerKey, offset, offset + limit + 1);

        if (targetIds == null) {
    
            return null;
        }

        List<Map<String, Object>> list = new ArrayList<>();
        for (Integer targetId : targetIds) {
    
            Map<String, Object> map = new HashMap<>();
            User user = userService.findUserById(targetId);
            map.put("user", user);
            Double score = redisTemplate.opsForZSet().score(followerKey, targetId);
            map.put("followTime", new Date(score.longValue()));
            list.add(map);
        }

        return list;
    }

2、FollowController

    @RequestMapping(path = "/followees/{userId}", method = RequestMethod.GET)
    public String getFollowees(@PathVariable("userId") int userId, Page page, Model model) {
    
        User user = userService.findUserById(userId);
        if (user == null) {
    
            throw new RuntimeException("该用户不存在!");
        }
        model.addAttribute("user", user);

        page.setLimit(5);
        page.setPath("/followees/" + userId);
        page.setRows((int) followService.findFolloweeCount(userId, ENTITY_TYPE_USER));

        List<Map<String, Object>> userList = followService.findFollowees(userId, page.getOffset(), page.getLimit());
        if (userList != null) {
    
            for (Map<String, Object> map : userList) {
    
                User u = (User) map.get("user");
                map.put("hasFollowed", hasFollowed(u.getId()));
            }
        }
        model.addAttribute("users", userList);// 里面存了user、followTime、hasFollowed

        return "/site/followee";
    }

    @RequestMapping(path = "/followers/{userId}", method = RequestMethod.GET)
    public String getFollowers(@PathVariable("userId") int userId, Page page, Model model) {
    
        User user = userService.findUserById(userId);
        if (user == null) {
    
            throw new RuntimeException("该用户不存在!");
        }
        model.addAttribute("user", user);

        page.setLimit(5);
        page.setPath("/followers/" + userId);
        page.setRows((int) followService.findFollowerCount(ENTITY_TYPE_USER, userId));

        List<Map<String, Object>> userList = followService.findFollowers(userId, page.getOffset(), page.getLimit());
        if (userList != null) {
    
            for (Map<String, Object> map : userList) {
    
                User u = (User) map.get("user");
                map.put("hasFollowed", hasFollowed(u.getId()));
            }
        }
        model.addAttribute("users", userList);

        return "/site/follower";
    }

    private boolean hasFollowed(int userId) {
    
        if (hostHolder.getUser() == null) {
    
            return false;
        }

        return followService.hasFollowed(hostHolder.getUser().getId(), ENTITY_TYPE_USER, userId);
    }